Caitlyn Jenner wowed the world with her glam debut on the cover of Vanity Fair, but stepson Rob Kardashian had no idea who it was when he first saw the picture.

Older sister Kim recalled how she sent her reclusive brother the photo in a mass text, prompting the reaction: "Who is this woman? And why do I care?"

But don't worry, he wasn't bagging out Caitlyn. In fact, it was rather the opposite – Kim explained the adorable moment to Access Hollywood at the CFDA Awards in New York. Naww, we're glad Caitlyn has such a supportive family!

The 65-year-old, formerly known as Bruce, revealed herself as a woman for the first time in a glossy Annie Leibovitz shoot for Vanity Fair.

In the 22-page spread, Caitlyn talks candidly about her transition, including a painful 10-hour facial-feminisation surgery and her "controlling" marriage to Kris Jenner. Watch Caitlyn talk about finally being "free" in this behind-the-scenes video from the shoot:

Caitlyn has cracked 2.15 million Twitter followers in one day, after yesterday's world record of one million followers in just four hours.

The Olympic gold medallist wrote: "Another Jenner world record, and at 65? Who'da thought! Humbled and honoured to have reached 1M followers in 4 hrs. Thank you for your support."